1. Field of the Invention
This invention relates generally to thin film electronic components and, more particularly, to thin film electronic components having precise parameters.
2. Description of the Related Art
Multi-chip modules (MCMs) require micro-miniature electronic components to achieve their greatest potential for performance and reduced size. For example, many MCMs require terminating resistors that can be placed in close proximity to the actual point of the electrical run termination, and micro-analog, high speed digital, and microwave circuits often need resistors to trim their gains, terminate their runs, and bias their thresholds. Conventional electronic components are frequently chips which are too large, occupy too much substrate space, and limit routing options.
Thin film deposition of resistors using conventional techniques on ceramic surfaces has been difficult, and resistors have not been deposited on polymer surfaces. Thin film resistor fabrication is complicated because each resistor deposition is slightly different, and the sheet resistance is not uniform throughout an underlying surface. Variabilities of 4%-10% are common because of variables in the resistor sputtering conditions. Therefore, for precision resistors, each resistor must be measured and, if not within tolerance, requires customized artwork based upon the characteristics of the deposition. Subsequent trim operations on ceramic surfaces can be used, but these operations require special equipment and are expensive. Plasma etching (such as CF.sub.4 or CF.sub.4 +O.sub.2), chemical or heat oxidation, or chemical anodizing can also be used to increase resistor values, but are not efficient for changing a plurality of resistors because a photoresist and etch step would be required for each individual resistor and result in increased processing time and expense.
It would be desirable to have a method of mass trimming of thin film electronic devices which enables highly accurate and close tolerance multi-chip module component fabrication.